I did a search on battery power supplies, but...

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I poked around for awhile with the search about battery supplies, but I didn't get exactly what i was looking for.

What are the pros/cons?

Also, what kind of specs do I need for a sealed lead acid batt.

48V (or 2 24v, 4 12v)?
what about Ah ratings? does that mean how many amps the thing can put out in one hour? What do I need for like, 3 hours listen time without the charger on? (not that i have that much time, but I'd rather have too much than not enough)

Sorry that I'm a complete noob at this stuff.
 
7ah slas are the best and cheapest to find and 4 of those should provide many hours of power.I have 8 of those for dual mono PS and do not need to recharge for days(for a gainclone).Thoroughly recommended - huge difference in sound quality.Some just buy off the shelf chargers and switch them around or make 4 separate regulators per LM317/137 schematics.Ideally you need current and voltage regulation (two regs each batt)but you could manage with just low current regulation.
 
Thanks for all your quick replies guys...

So for a few hours of listen time, 4 12v 5ah batteries would be 20ah.

Looking over the data sheets at nat. semi. it looks like 48v is a little much? or am i just not knowing how to interpret the graphs. Also, does anyone know the typical current draw these chips produce? (lm3875 in particular)
 
So for a few hours of listen time, 4 12v 5ah batteries would be 20ah.

Looking over the data sheets at nat. semi. it looks like 48v is a little much?

Not quite - you use 2 batteries per channel (for a stereo gainclone) to give +/- 24V per channel. Each battery will still give 5 amps per hour.

Have a look at this thread for a quick start:

click here

I have used batteries in a phono stage and they do give a very smooth sound.
 
This graph shows available power levels:
 

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I used an amplifier with a battery powersupply once.
A Metaxas clone, with a powersupply setup that Fred Gassman in Switzerland made for the original power amplifier.

Dont know if there is still some info on Gassman's site.
Nice ones for power amps are sealed maintenance free batteries.
For my boat i have used AcDelco's, in 5 AmpHour theirs should be great too if they make 'm.

I used a charger circuit from elektor that selected the battery it charged, that way you only need one charger, with a drop charger.
 
Try the batteries. In a direct comparison I found them different sounding from AC but not necessarily better.

In my setup I could do hot switching between AC and battery supplies. I used a heavy duty DPDT switch (rated for 10A) that switched between rectifier bridges and batteries. The caps were 1000uf Panasonics soldered at the chip pins, so they were always in circuit. I don't think the switching would be friendly without some reservoir caps in circuit all the time. It was important to find a switch that changed contacts on both poles at exactly the same time, otherwise a pop was heard through the speakers when switching.

With batteries, the bass was more defined and the music held together better through complex passages. Unfortunately, it was a little wiry sounding in the midrange compared to AC. I went back to AC simply because I had borrowed the batteries and had to return them. In the long term I'm not certain which I would have decided was better.
 
Ok, so I want around 5-10ah thats fine, and I'll be using SLA type, thats decided with individual chargers.

So now I need to determine the voltage I'm gonna run. I will be bi-amping these speakers, with the top end being a 4ohm Raven R1, and the bottom as yet undecided, but some form of TL, maybe an Adire Extremis. So I'm thinking 4 mono amps, two of which would be at 24V, while the other two would be at 36V? So I could run 2 12v's on the 4 ohm one, and 3 12v's on the 8ohm amp. Does this sound logical?


Peter "And using AC power with 100u BG N caps (only) is still better." In what sense, convenience or sound?

thanks for the advice!
 
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